A variety of quinolinecarboxaldehydes have been reacted with arenes in the
Bronsted superacid, CF3SO3H (triflic acid) to give condensation products in
good to excellent yields (52-99%). The quinolinecarboxaldehydes are signif
icantly more reactive than 2-naphthalenecarboxaldehyde. It is proposed that
the increased reactivity is due to the formation of dicationic, electrophi
lic intermediates.